Until recently crop farm management has had little choice but to assume that fields are essentially homogeneous across their entire areas and has had to apply farming inputs (e.g., tillage techniques and extent, application of fertilizers and herbicides, and other working of soil and crops) at uniform rates over an entire field or set of fields. Recent technological developments within the agricultural community, however, now allow crop production to be optimized by learning and responding to spatial variations in soil conditions, as well as in other properties, that commonly exist within any given farming field. By varying the farm inputs applied to a field to compensate for local variations or anomalies within the field, a farmer can optimize crop yield and quality by providing the amount of input needed at a specific site. An additional benefit is reduction of potential environmental damage or degradation due to, for example, erosion, pesticides, or herbicides. This management technique has become known as precision, site-specific, prescriptive, or spatially-variable farming.
Precision farming requires the gathering and processing of data relating to site-specific characteristics of a field. These data may be loaded in a first data base, such as a geographic information system (GIS) program, and used to generate a prescriptive map. The prescriptive map may be a second data base defining a set of farming inputs or other operations to be performed spatially variably in response to the spatial variations found in the measured data of the first data base. While crop data are useful information for this purpose, they are essentially an end effect and the more causal relationship of site-specific soil analysis data are therefore of great importance. Generally, such data are obtained from analyses of multitudinous soil samples gathered from a field in, typically, a grid pattern.
There are many variations in combinations of procedures in which samples may be acquired, locationally identified, and analyzed. Various procedures may also be used to report or log analysis data, and these data may be used in some way to cause various portions of a field to produce in a more nearly uniform manner than if the field were treated with unvarying inputs as though it were homogeneous. The discussion below does not describe all such possible combinations, and is intended only to illustrate some which are representative.
Methods of obtaining discrete, site-specific soil samples have ranged in the prior art from a man walking into a field carrying a shovel and a pail to take at most a few samples, to a mobile probe or augur system mounted on an off-road vehicle and provided with a device to place each sample into a separate container. Heretofore, none have related to the obtaining of soil samples from a moving vehicle; that is, in the prior art, if the sampling device is vehicle-mounted the vehicle must come to a stop and remain stopped while the sample is acquired. Since generation of a prescriptive map in precision farming requires the gathering of many soil samples to discover and adequately delineate variations within a field, the work vehicle has to make many such stops. Although the costs of labor, fuel, and vehicle amortization and maintenance make a separately performed traversing of a field for the purpose of obtaining a multitude of soil samples a costly operation, it has not heretofore been practical to eliminate or reduce that cost by combining such a soil sampling operation with another farming operation, such as tilling or harvesting, because the frequent stops required would unduly interfere with performance of the approximately constant-speed farming operation. As will be seen below, one aspect of the present invention addresses this problem.
Site-specific soil sample analysis requires the collecting not only of soil analysis data, but also of locational data describing from where within the field each sample was obtained. While this can conceivably be done using traditional manual measuring, triangulating, or surveying methods for a few sample sites, it has been found more practical to use Global Positioning System (GPS) or Differential Global Positioning System (DGPS) techniques and devices, which are available and sufficiently accurate and repeatable. GPS and DGPS antennae, receivers, and signal conditioning I/O devices may be mounted to agricultural vehicles and interfaced to mobile control, computing, and datalogging devices.
Analysis is generally done later (off-line) in a laboratory. Sample site locational information may be marked on sample containers for later correlation with analysis data, or sample containers may be numbered or otherwise uniquely identified and those identifications tabulated with corresponding locational descriptions. In either case, the data correlation is a separate operation with an attendant cost.
Particularly in the harvesting of grain crops, grain flow rate into a harvesting machine's hopper and grain moisture content level are sometimes measured as an indication of crop yield. This measurement is most easily done in real time with transducers or measuring devices producing data signals representative of grain flow rates and moisture levels. These data may be logged into a data base in computer memory or otherwise recorded in real time, but the soil analysis data, obtained later off line, must be merged into the same database when they become available.
These data, as well as any other which may be desired and available, may be used to generate or update a precision farming prescriptive map. Prescriptive map data may be loaded in a portable memory device such as a diskette or PCMCIA card, which may then be used in a computer or PLC on board the vehicle to provide site-specific control setpoints to an on-board proportional control system which, with suitable signal conditioning and actuators, controls rate of farm input to the field in conformance with the prescriptive map.
The effect of repeatedly (e.g., annually) providing prescriptive varied farm inputs to a field is at least partially cumulative for some types of field spatial variation, providing a smoothing effect on field spatial variations after some repetitions of the precision farming cycle from tillage to harvest. The cumulative effect also makes it beneficial, however, to repeat the site-specific soil analysis at least annually in order to not oversupply field inputs to sites or areas which still show beneficial effects from previous spatially-varied input operations. The cost of a separately performed traversing of the field for soil sampling purposes alone would therefore be incurred annually. Accordingly, it would be desirable to provide a system for obtaining and locationally identifying site specific soil samples from an agricultural field while work is being performed in the field.